Explainer change for separate rate-limits for embedded site

Author: linnan-github

EVENT.md

@@ -980,6 +980,10 @@ were reported.
 
 In order to achieve the privacy goals listed above the API has various rate limits, which can be found [here](https://github.com/WICG/attribution-reporting-api/blob/main/params/chromium-params.md) for Chromium.
 
+Note: Browsers may choose to allow separate rate limits for the embedded site 
+for specific use cases (for example, [AMP](https://amp.dev) pages rendered by
+an AMP cache/viewer provider).
+
 ### Trigger Data
 
 Trigger data, e.g. advertiser-side data, is extremely important for critical use

index.bs

@@ -1872,6 +1872,8 @@ To <dfn>check if cookie-based debugging is allowed</dfn> given a
 To obtain the <dfn export for=node>context origin</dfn> of a [=node=] |node|, return |node|'s [=node navigable=]'s
 [=navigable/top-level traversable=]'s [=navigable/active document=]'s [=origin=].
 
+Note: The user agent MAY return the embedded origin for specific use cases.
+
 <h3 id="obtaining-randomized-response">Obtaining a randomized response</h3>
 
 To <dfn>obtain a randomized response</dfn> given |trueValue|, a [=set=] |possibleValues|, and a